1. Field of the Invention
The present invention relates to a tube connecting apparatus and a tube connecting method that cuts and then connects flexible tubes, and in particular relates to a tube connecting apparatus and a tube connecting method that melts at least two flexible tubes by heat and then connects the tubes under a sterilized condition.
2. Description of Related Art
Conventionally, in a case that tube connecting between a blood-collecting bag and a blood-component bag in a blood transfusion system, exchanging between a dialytic-fluid bag and a waste-fluid bag in continuous ambulatory peritoneal dialysis (CAPD) or the like is carried out, it is necessary to connect (join) tubes under a sterilized condition. An example of such an apparatus for connecting tubes under a sterilized condition is disclosed in JPB 61-30582. This tube connecting apparatus is equipped with a pair of holders (blocks) capable of holding two tubes to be connected in parallel and a cutting plate (plate-shaped heater element) capable of moving across the tubes which are placed between both of the holders. In the tube connecting apparatus, the cutting plate is heated and moved to melt and cut the tubes in a state that the two tubes are held in parallel and in an opposite direction in grooves which are formed at the holders, then one of the holders is moved in a diameter direction (row direction) of the tubes to coincide cut ends of the tubes to be connected each other, and the cutting plate is extracted by moving it to an evacuated position to fuse (melt and connect) both of the tubes.
Further, a tube connecting apparatus having a first clamp and a second clamp which hold two tubes in a parallel state, which employs the same tube connecting method as the above apparatus in order to improve reliability of tube connecting, and which is equipped with a first clamp movement mechanism that moves the first clamp in parallel to the second clamp, namely, that carries out merely forward or backward movement for advancing or retracting the first clamp, and a second clamp movement mechanism that moves the second clamp merely in a direction that the second clamp approaches/separates to/from the first clamp, is disclosed in JPA 6-91010.
Furthermore, an apparatus, which employs the same principle of heating, melting and then connecting tubes each other under a sterilized condition by utilizing a cutting plate, yet which connects the tubes in a state that liquid in the tubes is kept contained without leaking the liquid even in a case that the liquid remains inside the tubes before the tubes are cut, is disclosed. For example, JPA 4-308731 discloses a technique that two tubes (a first tube, a second tube) are held on the same rotation locus respectively according to a pair of tube holders allowed to rotate relatively, after the two tubes are cut between the holders by a heated cutting plate, the tube holders are rotated such that a cut end face of one end side of the first tube aligns (corresponds to) a cut end face of another side of the second tube, and the cutting plate is evacuated to fuse both of the tubes. Moreover, a tube connecting apparatus which is capable of not only connecting tubes in a state that liquid inside the tubes is kept contained and sealed without leaking the liquid but which can realize downsizing of the apparatus and of parts for the apparatus due to a small moving amount of the tubes at the time of connecting the tubes, is also disclosed. For example, JPA 9-154920 discloses a technique that two tubes to be connected are accommodated and held in two tube-holding assembly (a first tube-holding assembly, a second tube-holding assembly) in a contacted (piled) state with each other, after the two tubes are cut by a heated cutting plate, the second tube-holding assembly is rotated by 180 degrees relatively to the first tube-holding assembly such that cut end faces of the tubes are replaced with each other for alignment, and the cutting plate is evacuated to fuse both of the tubes.
However, in the conventional tube connecting apparatuses, even in any embodiment of the apparatuses in which the two tubes are arranged in parallel in a horizontal or vertical direction in a separated or contacted state, if liquid inside the tubes includes protein such as blood or the like, residual liquid inside the tubes between the two tube-holding assemblies (holders) remains at the end faces of the tubes to be connected when the tubes are cut by the cutting plate. For this reason, there is a problem in that connecting strength between the tubes is remarkably weakened. Namely, in the conventional apparatuses, in a case that liquid is contained and sealed in either one of the tubes, since the tube end face of one side thereof is moved in a state of contacting the cutting plate at the time of moving the tube-holding assembly so as to face the end portions of the tubes to be connected each other via the cutting plate and the residual liquid in the tubes is excluded or removed to some degree at this time, it is possible to connect the tubes each other although connecting strength thereof is lowered. However, they could not connect two tubes each other stably in a case that both of the two tubes contain and seal liquid such as blood or the like.